This invention relates to a circuit board support arrangement for electronic equipment.
FIGS. 1, 2 and 3 illustrate one example of the conventional circuit board support arrangements for supporting circuit boards within an electronic equipment housing.
In the figures, the electronic equipment housing 1 comprises a chassis 2, a cover plate 3, a front panel 4 and a bracket 5. The chassis 2 is composed of a bottom plate 10, a rear plate 11 vertically extending from one end of the bottom plate 10, and a front plate 12 vertically extending from the other end of the bottom plate 10, so that these three plates 10, 11 and 12 together constitute a substantially U-shaped frame. The cover plate 3 is fixed at one end thereof to the rear plate 11 and at the other end thereof to the front panel 4 in a conventional manner. The electronic equipment housing 1 is provided with an arrangement for supporting one or more circuit boards 13.
The conventional support arrangement comprises a first support 14 and a second support 15 for supporting a plurality of circuit boards 13 therebetween. Each circuit board 13 has a first end 16 (the righthand end in FIG. 1) and a second end 17 (the lefthand end in FIG. 1). The first support 14 comprises a fixing member 18 for rigidly supporting the first end 16 of a circuit board 13 on the rear plate 11 of the housing 1. The fixing member 18 is substantially an elongated member extending along the first end 16 of a circuit board 13 and firmly secured to the first end 16 by means of screws 19 and tabs 20. The lower end of the fixing member 18 is inserted into a slit formed in the bottom plate 10 of the housing 1 and the upper end of the fixing member 18 is secured to the rear plate 11 by a screw 21. The second support 15 comprises a base plate 22 which is provided with a plurality of fitting projections 23. The bracket 5 is provided with a plurality of fitting holes 24 which are located in a corresponding relationship with respect to the fitting projections 23. The base plate 22 is attached to the bracket 5 through the fitting projections 23 and fitting holes 24. The base plate 22 is further provided with a plurality of elongated slot members 25 for slidably receiving therein the second ends 17 of the circuit boards 13, each slot member 25 being integrally moulded with the base plate 22.
The reason why the circuit boards 13 are removably supported by the second support 15 is that the circuit boards are often required to be easily replaced by other circuit boards having different functions in accordance with the need of end users.
Referring now to FIG. 3, in the conventional circuit board support arrangement for electronic equipment, the chassis 2 may be temporarily deformed or twisted due to shocks such as vibration or falls during transportation in such a manner that the first support 14 and the second support 15 are moved away from each other as shown in FIG. 3. During this time, the second ends 17 of the circuit boards 13 tend to slide out from the slot members 25 of the second support 15.
When the above stated shocks cease, the chassis 2 restores its original shape, whereby the first and second supports 14 and 15 return to their respective original relative positions. However, the second ends 17 of the circuit boards 13 do not always slip back into their respective slots in the slot member 25. In the case where a circuit board 13 slips out of the slot of the slot member 25 completely and fails to slip back into its respective slot, it is no longer supported by the second support 15, but rather is only supported by the first support 14. Due to such shocks as vibration and falls, as above described, which may subsequently occur, the partially supported circuit board 13 may come into contact with the side plates of the housing or other circuit boards in its vicinity, thereby causing it to be damaged.